Digital signals are used for transmitting information over a network. For example, the digital signals may be transmitted from a digital transmitter. In operation, the digital transmitter receives in-phase (I) and quadrature-phase (Q) input signals and processes the I and Q input signals through various processing stages, including a power amplifier stage. The processed I and Q input signals may then be transmitted as a digital signal. Various digital signal transmission techniques may be implemented for processing and transmitting digital signals.
Conventionally, a polar, a Cartesian IQ, or a four-phase IQ technique are used for digital signal transmission. The polar technique converts an input signal (I, Q) into polar coordinates prior to transmission. The Cartesian IQ technique uses the in-phase (I) and the quadrature-phase (Q) of the input signal for determining a transmission scheme within a square-shaped transmission region. The four-phase IQ technique uses a diamond-shaped transmission region along the zero-degree axis and 90-degree axis, which is a variation of the Cartesian IQ method.
Each of these conventional digital signal transmission techniques suffer from different problems. For example, a disadvantage of the polar method is that it is processing intensive, although it yields a maximum range of transmission signals within a full circle. Disadvantages of the Cartesian IQ method include inefficiency for points not along I or Q vectors. Finally, the four-phase IQ method suffers from inefficiencies in transmission not along the zero-degree axis or 90-degree axis.
It is therefore desirable to implement a modulator that overcomes these deficiencies by reducing processing intensity while also improving transmission efficiency.